Effect of nanocrystal size on anti-stokes photoluminescence in lead halide perovskites

We report size-dependent anti-Stokes photoluminescence (ASPL) of methylammonium lead bromide (MALB) perovskite nanocrystals (NCs) under resonant laser excitation. The ASPL efficiency has been found to be stronger for a sample with 6 nm sized MALB NCs. The effect has been explained by the electron–phonon interaction, which results in simultaneous photon–phonon absorption followed by the radiative recombination through excitonic states in MALB NCs. The obtained results can be useful for potential application of MALB NCs in optical cooling.